Unprecedented detoxification of the cruciferous phytoalexin camalexin by a root phytopathogen

The unusual metabolism of the phytoalexin camalexin by the root rot fungus Rhizoctonia solani Kuhn is reported. This transformation proceeded via 5-hydroxycamalexin, further transformed into 5-hydroxyindole-3-carbonitrile and 5-hydroxy-2-formamidophenyl-2′-thiazolylketone. Most importantly, the metabolites resulting from transformation of camalexin were significantly less toxic to the fungus than camalexin